Rotating vane wheel atomizer



Dec. 3, 1957 J. E. NYROP 2,815,246

ROTATING VANE WHEEL ATOMIZER Filed Sept. 14, 1953 2 Sheets-Sheet l Dec.3, 1957 J, NYROP 2,815,246

ROTATING VANE WHEEL ATOMIZER Fig.4

Filed Sept. 14, 1953 2 Sheets-Sheet 2 M Fig.5

37 38 W77, 1 I it ,J 36 35 32 INVENTOR.

ROTATING VANE WIEEL ATOMIZER Johan Ernst Nyrop, Hellerup, nearCopenhagen, Denmark Application September 14, 1953, Serial No. 379,891

Claims priority, application Great Britain September 24, 1952 4 Claims.(Cl. 299--63) The invention relates to a rotating vane wheel atomizercomprising at least two vane wheels concentrically rotating in the sameor in opposite directions relative to each other at difiering relativevelocities, each of the vane wheels independently mounted and drivenfrom a common central shaft and radial channels in each of the vanewheels through which a liquid or fluid with a content of solids is fedfrom a fluid supply means and is flung out in atomized form into thechamber of a spray drier or the like in which the particles are dried bymeans of a drying medium such as hot air or in other ways treated forobtaining a finely comminuted dry powder.

Atomizers with rotatable vane wheels having a space intended to receivethe medium to be atomized inside of the inner edges of the vanes of thevane wheel are known. Such atomizers are well suited for atomizingliquids of a viscosity which is not too great, e. g. aqueous solutions,and they are used for instance for the production of powders of varioussubstances by atomizing a solution of the substance into a dryingchamber wherein a heated air current causes the evaporation of thesolvent so that the solid is recovered in the form of solid particles ofthe substance dissolved in the liquid supplied.

These known atomizers cannot, however, be used for atomizing too highlyviscous liquids or for powder agglomerates of a slight liquid content,as it appears that the viscous liquids are flung off from the outeredges of the vanes, as threads coherent whereas the powder agglomeratesare flung ofi in lumps.

The main purpose of the invention is to provide an atomizer by whichsuch highly viscous liquids or agglomerates may be effectively atomized.

The atomizer of the present invention is provided with a rotating vanewheel with an annular space between the shaft of the vane wheel and theinner edge of its vanes. The annular space is adapted to receive themedium to be atomized. A further vane wheel is provided co-axially withsaid vane wheel and surrounding the same. A narrow space between theinner edges of the vanes of the latter wheel and the outer edges of thevanes of the former wheel is thereby provided. The vane wheels aredriven by driving means in such a way that two successive wheels havemutually different rotational speeds.

In the atomizer according to the invention, there is used a further vanewheel rotating concentrically around the former with a narrow spacebetween the outer edge of the former and the inner edge of the furthervane wheel and so that the two wheels adjacent the same narrow spacemove at different velocities, and atomization is obtained of such highlyviscous liquids or powder agglomerates of a slight moisture contentwhich most probably is due to the fact that a crushing or a kind ofgrinding of the material takes place.

An object of the invention is to provide an atomizer having a rotatingvane wheel with an annular space between the shaft of the vane wheel andthe inner edge of its vanes, which space is intended to receive themedium to be atomized, wherein co-axially with said vane wheel andsurrounding the same :a further vane wheel is provided with a narrowspace between the inner edges of the vanes of the latter wheel and theouter edges of the vanes of the former wheel, means for driving the vanewheels in such a way that two successive wheels have mutually differentrotational velocities, and wherein the outer vane wheel is positioned tobe freely rotatable in relation to the inner vane wheel so that it maybe driven by means of the medium flung out from the inner wheel duringthe operation of the atomizer.

Other and further objects of the present invention will appear from themore detailed description set forth below, it being understood that suchdetailed description is given by way of illustration and explanationonly and not by way of limitation, since various changes therein may bemade by those skilled in the art without departing from the scope andspirit of the present invention.

In connection with that more detailed description, there is shown in thedrawings, in

Figure 1, a view partly in section and partly in elevation of the deviceof the invention,

Figure 2, an enlarged sectional elevation view of the vane wheels ofFigure 1,

Figure 3, a plan view of a section of the structure of Figure 2, partlyin elevation and partly in section,

Fig. 4, a sectional elevation view of a modified form of the vane wheelsof Fig. 2; and

Fig. 5, a sectional elevation view of another modified form of the vanewheels of Fig. 2.

In Figure 1 there is shown the general relationship of parts of a spraydrier provided with an atomizer in accordance with the invention andsaid atomizer comprises a motor 2 mounted upon the top wall 1 of theatomization chamber, a direct drive shaft 3 from the motor which drivesthe vane wheels and a series of supply pipes 5 which supply the viscousor concentrated liquid which is being atomized.

Through the conical bottom wall 39 of the chamber a supply pipe 40 isled into the chamber for supplying a drying medium such as hot air tothe chamber. Said pipe has a bend so that it extends axially of thechamber for most of the height thereof and its mouth is disposedco-axially beneath the atomization wheel at an appropriate distance fromthe same in a well known manner. At the mouth the supply pipe may beprovided with a guiding member 41 for guiding the drying medium so thatit flows out into the chamber as a rotating flow for intimatelyintermingling with the atomized particles flung out from the wheel fordrying the particles so as to obtain a dried powder.

The particles sink down together with the drying medium and part of thedried powder is deposited on the cone shaped bottom wall from which itmay be removed through an outlet 42.

The part of the particles which do not settle on the bottom wall, as arule the greater part, follows the stream of drying medium sucked offthrough an outlet 43, whereupon the particles may be separated from thedrying medium by any appropriate means not shown.

The atomization chamber is shown in Figure l as being of cylindricalshape with a conical bottom part and the motor is mounted at the top andcenter of the upper part of the device to illustrate the invention inone of its simpler forms. However, it should be appreciated that thechamber may be modified as to shape, and that the mounting of the motormay be modified to provide a direct or indirect drive as is known in theart. The motor may thus be coupled with the shaft 3 by means ofappropriate gearing for either greater or reduced rotational speeds ofthe shaft as is desired. Further, the inlet pipes 5 are shown as passingthrough the top wall 1 of the atomizer, but these pipes may, if desired,lead through the sides of the atomizer at a position above the vanewheels and near the top wall 1.

It should be understood that the atomizer of the invention is notlimited for use with spray drying but may also be used for otheroperations that may be performed by means .of similar devices. Forinstance the apparatus or modifications thereof may be used inmanufacturing powders by spray crystallization. In this case the dryingmedlum should not be hot air but on the contrary it should be a coolingmedium. Further it is possible to obtain chemical reactions between theatomized fluid and a gaseous agent supplied in lieu of or simultaneouslywith the above mentioned drying and/or cooling media.

The supply of the drying medium or the like may be obtained in otherways than shown and described above. For instance it may be suppliedfrom above or on a level with the atomization wheel through appropriatechannels or mouth pieces. It may alternatively be supplied from beneaththe atomization wheel through one or more mouthpieces through thesidewall of the atomizer, tangentially to the wall or not, as desired.

The construction of the .vane wheels is shown in Figures 2 and 3. On theshaft 3 an atomization wheel 4 is secured by means of a nut and a jamnut 6 which atomization wheel comprises a hub '7 and an annular member8, which is shaped in one piece with the 'hub 7 or fi-xed thereto in anysuitable way. In the annular member 8 channels -9 are milled out. Thevanes of .the wheel are constituted by the lagging walls of saidchannels, when the wheel is rotated. As indicated with a dotted screw 10an annular cover plate 11 may be fastened to some of the partitions 12'separating the channels 9. This cover plate may also constitute part ofthe body of the wheel or it may, as the case may be, completely bedispensed with. The inner edges of the vanes are at some distance fromthe shaft 3 so that an annular space is formed between the vanes and theshaft, receiving the means for supply of the medium to be atomized. Thismeans is -in Figs. 2 and 3 diagrammatically shown as a single supplypipe but it should be understood that the supply means is notso limited,any means for obtaining an appropriate distribution of the medium to thevanes could be used. When the wheel is rotated at a great speed by meansof the motor, the medium supplied in the annular space will by means ofthe centrifugal force be flung out into thechannels 9 and pass alongtheir lagging .walls, and be fiung away from the outer edges of thelatter.

In constructions of the prior art which contain but a single vane wheelprovided with the annular space between the vanes of the wheel and theshaft in order to deliver the liquid medium being atomized to theperiphery of the wheel where it is atomized under the action ofcentrifugal force :through the channels provided in the wheel, theatomization devices were severely limited for the use of liquid of lowviscosity and low solids content. The channels and spaces became cloggedin these single vane wheel devices by the concentrating action obtainedupon the viscous liquid during the centrifuging operation of thedevices. At .the outer edges of the vanes, the :lower density liquidflung out and separated from the solids by the action of centrifugalforce causes the formation of threads and lumps of pasty solidsandthedesired atomization is defeated.

This drawback in the construction and performance of the prior artdevices is overcome in accordance with the invention by providing atleast one additional atomization Wheel comprising a hub 15, aplate-shaped part 16 and an annular .part 17 with channels 18 formingvanes as is shown in Figures 2 and 3. This further atomization Wheel ispositioned on the hub 7 of the first atomization wheel by means ofbearings which are, in the embodiment shown, in the form of ballbearings 19. Between the annular parts 8 and 17 of the inner and outerwheel respectively a narrow space 29 has been maintained.

In the hub 15 of said further atomization wheel a number of openings arearranged only one of said openings being shown in the drawings andidentified by the reference 20. These openings are for sucking in airwhen the wheel is rotated, and this sucking in of air, shown in Figs. 2and 3, improves the atomization.

The mode of action of the atomizer is as follows: The shaft 3 is rotatedby means of a suitable motor, so that the vanes, formed by means of thechannels 9 will rotate at a number of revolutions of e. g. 10,000revolutions per minute. The medium to be atomized is supplied throughthe supply pipe 5, of which there may possibly be more than one, and/,orfurther distribution members as already mentioned, and thus the mediumflows into the space 14 from where it is by means of the centrifugalforce flung out and, also by means of the centrifugal force, driven outalong the lagging walls of the channels 9 from the outer edges of whichthe medium is then flung out to impel the walls of the channels 18 ofthe outer vane wheel, which walls are facing backwards relative to thedirection of rotation of the first wheel. The outer wheel is thus causedto rotate by turbine action. The medium flows out along said walls ofchannels 13 and is finally flung off their outer edges. Experimentsprove that even in case of very highly viscous liquids or conglomeratesof solid particles, said flinging off results in comminut-ion andatomization, which it is presumed is due to the fact that a breaking ora kind of grinding of the medium flung off in coherent strings or lumpsfrom the outer edges of the channels '9 takes place in the space 29 onaccount of the relative velocity between the two vane wheels.

It can easily be ascertained that such a relative velocity occursbetween the two vane wheels, since apart from friction, the medium willleave the channels 18 with the same kinetic energy as that with which itwas supplied to said vanes so that m v =m v where m and me are themasses of the medium supplied and led away, respectively, per unit oftime, and v and v are the speed of the medium supplied and led awayrespectively. m and m are equal and consequently also v and v areequals.

These two velocities are equal to the peripheral velocity of the innerwheel and the outer wheel, respectively, and accordingly the product ofrevolution number and outer diameter of either Wheel is the same, sothat the number of revolutions of the outer wheel is smaller than that.of the inner .wheel, whereby a relative movement is provided betweenthe edges of the inner wheel and the edge of the outer wheel adjacentthe narrow annular space 29.

In the above friction is disregarded, but it will easily be understoodthat the friction as well as any other imaginable influence from outsidewill entail a reduced number of revolutions of the outer wheel and thusan inre sed r lat e v m y- If, a c r i y, i i upp se t a the inner whe lhas a diameter of 20cm. and the outer wheel one of 28 em, the number ,ofrevolutions of the outer wheel will be about 7.000 revolutions perminute, the presum number of revolutions of the inner wheel being 10,000revolutions per minute.

The .embodiment described should only be regarded as an example ,as itsdetails may undergo .various modifications within the scope of theinvention. Thus, the hape o th channe forming the vanes o th o Whl mayhave any suitable form, and the number of them may also vary ,withinwide limits and also with a .view to the mutual relation between thenumber of vanes of the two wheels.

The bearing may be shaped in different ways. For instance other typesthan the bearings 19 shown may be used, and further the "bearing of theouter wheel does not necessarily have to be mounted directly on the hubof the inner wheel, but may be mounted on the shaft 3 or a projection ofthis shaft. Further, it might be possible that the outer wheel bepositioned in a bowl with mercury.

While in the described embodiment it is supposed that the outer wheel isoperated by turbine action by means of the liquid flung off from theinner wheel, it is also possible to construct the atomizer so that theouter wheel is also motor-driven. This is diagrammatically indicated inFig. 4, wherein the inner wheel is designated by 21 and the outer wheelby 22.

The inner wheel 21 is secured to the end of a hollow shaft 23, and theouter wheel to the end of a shaft 24 between a bushing 25 which issecured with a pin 26 and a nut 27 with a jam nut 28. The shaft 24 ispositioned concentrically inside the hollow shaft 22. The two shafts 22and 23 are mounted in bearings of any suitable type not shown on thedrawing and are interconnected through a gear G, which is onlydiagrammatically indicated and are driven through the latter by means ofa motor M also only shown diagrammatically.

By means of the gear G the two wheels 21 and 22 will be operated withsuitable mutual rotational velocities. The two wheels 20 and 21 mayeither rotate in the same or in the opposite direction, and the innerwheel may either be operated at a greater or a smaller velocity thanthat of the outer one. It is noted that the same rotational velocity,but opposite direction of revolution may also be regarded as themutually different rotational velocities, the essential feature beingthat a relative movement takes place between the two wheels and furtherthat; the velocities are so adjusted that particles flung oflf from theinner wheel cannot pass the channels of the outer wheel withoutimpelling the inner walls.

A particularly efficient and simply constructed embodiment with threevane wheels is shown in Figure 5.

This embodiment comprises, as is the case in Fig. 4, two vane wheels 31and 32 which are operated by the motor M, but here no gear for providingthe different rates of rotation is used since the vane wheel 32 issecured to the hub 34 of the vane wheel 31 by bolts 33. As in theembodiments shown in Figs. 2 and 3 a freely running vane wheel 35 ismounted on the hub by means of ball bearings 36.

Between the vanes 37 and 38 of the wheels 31 and 35 respectively thereis maintained a narrow annular space 37 and between the wheels 35 and 32a narrow annular space 38 is maintained.

Despite the essential simplicity of construction consisting in the twowheels 31 and 32 being secured to each other and rotating with the samerotational velocity, the new result is obtained and the wheel 35 runs inthesame manner as in Figs. 2 and 3 at a lower rotational velocity thanthe wheel 31, and hence the wheel 32 runs at a higher rotationalvelocity than the wheel 35, so that the two wheels adjacent the annularspace 38, viz. the wheels 32 and 35 have a mutual movement as is thecase with the two wheels adjacent the space 37, i. e. the wheels 31 and35.

It will be seen that the principle used in Fig. 5 may also be used incase the atomizer is constructed with more than three vane wheels,namely so that all the wheels having odd numbers-counted from theshaft-are firmly secured to the shaft, whereas the intermediate wheelswith even numbers are freely rotatable in relation to the former wheels,all the wheels with odd numbers thus having the same rotationalvelocities, viz. corresponding to the ratio between the outer diametersof the wheels in question.

The atomizer according to the invention is not limited to use foratomizing viscous liquids or conglomerates of solids, but may also beused for atomizing more easily flowing liquids as e. g. aqueoussolutions. This may be of particular importance in the production ofcoarser particles where it is desired to obtain a slow flinging out, andin order to use an atomization chamber of a comparatively smalldiameter. In this case the outer wheel should rotate more slowly thanthe inner one or it may be moved in the opposite direction to the innerwheel.

It is thought that the invention and its advantages will be understoodfrom the foregoing description and it is apparent that various changesmay be made in the form, construction and arrangement of the partswithout departing from the spirit and scope of the invention orsacrificing its material advantages, the forms hereinbefore describedand illustrated in the drawings being merely preferred embodimentsthereof.

What is claimed is:

1. An atomizer comprising a shaft, means for rapidly rotating saidshaft, a first vane wheel mounted on said shaft, said first vane wheelhaving an annular part coaxially surrounding said shaft, the internalsurface of said part defining together with said shaft and annular spacecoaxially surrounding said shaft, said annular part having ducts thereinextending from said annular space to the external circumference of saidannular part, partitions between each of said ducts separating saidducts from each other, said partitions constituting the vanes of saidfirst vane wheel, a second vane wheel mounted on said shaft having anannular part coaxially surrounding said first vane wheel, said annularpart of said second vane wheel having ducts therein distributed aboutthe axis of said part and extending from the internal circumference ofsaid part to the external circumference of said part, partitionsseparating said ducts from each other and constituting the vanes of saidsecond vane wheel, the inner edges of the vanes of the second wheel andthe outer edges of the vanes of the first wheel being spaced from eachother by a narrow space, one of said vane wheels being secured on saidshaft for rotation therewith and the other being journalled on saidshaft.

2. An atomizer as claimed in claim 1, wherein said second vane wheel isjournalled on said shaft and is freely rotatable in relation to saidfirst vane wheel.

3. An atomizer as claimed in claim 1, and a gearing device coupling thetwo vane wheels to each other.

4. An atomizer comprising a motor-operated shaft, a plurality of vanewheels, each wheel having an annular vane part, said vane parts havingducts therein extending from the internal circumference of said annularvane parts to the external circumference thereof, partitions separatingsaid ducts from each other, said partitions constituting vanes in thewheel, said annular vane parts of said wheels surrounding one anotherconcentrically and being disposed at the same level as seen at rightangles to the shaft, the ends of the vanes on adjacent wheels beingspaced from each other a narrow annular space between adjacent vaneparts, the vane wheel with a vane part at one side of each of saidspaces being secured to said shaft, the vane wheel with a vane part atthe other side of the same space being rotatably mounted on said shaft.

References Cited in the file of this patent UNITED STATES PATENTS2,357,050 McCrum Aug. 29, 1944 2,380,660 McKay July 31, 1945 2,737,276Wyndham Mar. 6, 1956 FOREIGN PATENTS 462,235 Italy Mar. 5, 1951

